private void btnNotGuncelle_Click(object sender, EventArgs e)
        {
            EntityNotlar ent = new EntityNotlar();

            ent.OgrID    = Convert.ToInt16(txtOgrID.Text);
            ent.Sinav1   = Convert.ToByte(txts1.Text);
            ent.Sinav2   = Convert.ToByte(txts2.Text);
            ent.Sinav3   = Convert.ToByte(txts3.Text);
            ent.Proje    = Convert.ToByte(txtProje.Text);
            ent.Ortalama = Convert.ToByte(txtOrtalama.Text);
            ent.Durum    = txtDurum.Text.ToString();
            BllNotlar.Update(ent);
            MessageBox.Show("Not Güncellendi");
            NotListele();
        }